The present invention relates to keyboard apparatus equipped with hammer structures pivotably provided beneath individual keys.
Examples of keyboard apparatus of the type equipped with hammer structures pivotably provided beneath individual keys are disclosed in Japanese Patent Application Laid-open Publication Nos. H9-198037 (hereinafter referred to as “patent literature 1”) and 2003-42206 (hereinafter referred to as “patent literature 2”). In the keyboard apparatus disclosed in patent literature 1 identified above, each of white and black keys is pivotably supported at its rear end portion by a frame and normally biased by a leaf spring. Further, a pivot lever, including a lever base and weight, is provided as a hammer structure beneath each of the keys, and the pivot lever is driven by a driving section provided on the key. The key is returned to its original position by the resilient force of the leaf spring as depression of the key is released.
In the keyboard apparatus disclosed in patent literature 2 identified above, each key is supported at its rear end support portion by a keyboard frame, a mass member of a hammer structure is disposed beneath the key, and the key and mass member are held by an S-shaped spring. The mass member is driven by a downwardly-projecting portion formed on the key. Also disclosed is a structure for pivotably holding each key by means of a V-shaped spring.
In electronic keyboard instruments equipped with movable sections, such as hammer structures, it is necessary to take into account installation of an electric wiring cable from a switch circuit board on which are mounted key switches for detecting ON/OFF states of individual keys of the keyboard apparatus. If the wiring cable is installed improperly, e.g., if the wiring cable contacts a movable component, such as a key, there would be encountered the problems that the key touch feeling is adversely influenced, mechanical noise, such as rubbing noise, occurs, and, in some case, the wiring cable is impaired to produce an electrical trouble. Further, if the wiring cable is taken into account with priority, there would arise the problem that the hammer structures etc. are subjected to design-related limitations.
In order to avoid unwanted contacts and interferences between the driving sections, such as the hammer structures and keys, and the wiring cable, it is conceivable to, for example, install the wiring cable so as to exit from opposite sides pf the keyboard; in this case, however, the wiring cable has to have an increased length for connection with a main circuit board. Particularly, in the case where a leaf spring (e.g., S-shaped spring) etc. are to be provided beneath each key as in the keyboard apparatus disclosed in patent literature 1 or 2, there arises another need to avoid interferences between the leaf springs etc. and the wiring cable.